Monoazo and disazo compounds with an active methylene coupling component



United States Patent MONOAZO AND DISAZO COMPOUNDS WITH AN ACTIVE METHYLENE COUPLING COMPONENT Paul Resnick, Brooklyn, N.Y., and Hsien Cheng Yao,

Dearborn, Mich., assignors to Interchemical Corporation, New York, N.Y., a corporation of Ohio No Drawing. Filed June 28, 1962, Ser. No. 205,873

5 Claims. (Cl. 260-176) This invention relates to azo compounds having extremely facile acetyl cleavage.

The new compounds are of the type that can be represented by the formula O Ar-N=NG'R wherein Ar is an aromatic ring such as phenyl, diphenyl naphthyl, etc., R' is an alkoxy or amino group, and R or R" is an alkyl group, an aryl group, or R and R" complete a ring structure. They are unique in having a very facile acetyl cleavage and thus serve as sensitive mild acetylating agents. No other substance need be added to initiate or to carry out the acetylating reaction. They also may be used as polymerization initiators.

The new azo compounds may be prepared in excellent yields and with clean reactions. In the coupling reactions weak bases are used, such as pyridine, picolines, quinoline, collidine, etc. Cleavage reactions of the compounds with water, ethanol, phenol, aniline, and acetic acid were studied and showed that an acyl cleavage and an azo to hydrazone conversion were involved.

EXAMPLE 1 a-Phenylazo-a-methyl-acetoacetic ethyl ester (A) 20 g. of alpha-methyl acetoacetic ethyl ester were dissolved in 200 ml. of a mixture of 50 ml. of pyridine and 150 ml. of water. The solution was cooled to 0 C.

(B) 13 g. of aniline were dissolved in 120 ml. of 5 N HCl and cooled to 0 C. A cooled saturated solution of sodium nitrite was slowly added with constant stirring until the equivalent of g. of solid sodium nitrite had been added.

B was then added dropwise to A with constant stirring, the temperature of the mixture being maintained at 0 C. When the addition was complete a yellow oily layer was on the bottom. The ice-cooled solution was extracted with ether. The extract was washed with very dilute ice-cold acetic acid followed by washing with several portions of ice water. The ether solution was dried over magnesium sulfate and the ether subsequently evaporated under vacuum. 27 g. of the crude product, a yellow liquid, were obtained. Further purification was accomplished by vacuum distillation, the principal fraction coming over at 138140 C. at 4 mm. of mercury. Some decomposition was observed. Analysis of the principal distillate showed C, 62.75%; H, 6.41%, and N, 11.17%. Theory required C, 62.80%; H, 6.46%, and N, 11.28%. The index of refraction was N =1.51158 at 22 C. The yield Was 78% of the theoretical.

EXAMPLE 2 u-Phenylazo-cyclopentanone-a-carboxylic acid ethyl ester Using the same procedure as in Example 1, phenyl diazonium chloride was coupled to cyclopentanone-acarboxylic ethyl ester. A yield of 92% of the crude "ice product was obtained after the evaporation of ether under vacuum. The index of refraction of the liquid product was N =L5477 and analysis showed C, 64.38%; H, 6.28%; N, 10.86%. Theory requires C, 64.61%; H, 6.20%; N, 10.81%.

EXAMPLE 3 a-Phanylazo-ot-methyl-acetoacetanilide Again using the same procedure as in the preceding examples phenyl diazonium chloride was coupled to alpha-methyl-acetoacetanilide. The product was recrystallized from a mixture of benzene and petroleum ether.

The melting point was 105-106 C. and the yield was Analysis showed C, 69.08%; H, 5.87%; N, 14.28%. Theory requires C, 69.14%; H, 5.80%; N, 14.23%.

EXAMPLE 4 a-Phenylazo-cyclopentanone-a-carboxanilide Again by utilizing the same method as before phenyl diazonium chloride was coupled with cyclopentanone-acarboxanilide. The product was recrystallized from a mixture of benzene and petroleum ether. The melting point was 104 C. and the yield was 90%. Analysis showed C, 70.24%; H, 5.53%; N, 13.60%. Theory re quires C, 70.33%; H, 5.57%; N, 13.67%.

EXAMPLE 5 Alpha-alpha'-bisphenyl-azo-alpha, alpha'-dimethyldiacetoacetic acid diethyl ester After the distillation 3 t 4 (Example 5) 2. a-pheny lrazo cyolopentanone a oa-rboxylic ethyl ester. (3H3 I (3H3 3. a-Pheny1aZo-a-methyl-acetoacetani1ide. 0: 0:0 4. =a-Pheny1azo-cyclopentanone-a-carboxanilide. HsC( 3N=N C 5 5. a,a' Bisphenlazo-a,m dimethyl-diacetoacetic acid I d1ethy1 ester, 5 (13:0 R f c: d b m E O C2H5 043211 e erences 1 e y e xammer Favrell, G.: Bull. Soc. Chim. (4) 47 (1930), pp. 1290- 1300 What 15 clarmed 1s: 10 1. A phenylazo compound. selected from the group z g f' Aromatlschen Dlazoverbmdungen conslstmg of a phenylazo cyclopentanone a carboxyhc Kalbu et all: Berichte, P. 1863 VOL 59 (1926).

ethyl ester, a-phenylazo-a-methylacetoacetanilide, oc- Linstead et a1 chem Soc J (London) t 1 phenylazo-cyclopentanone-a-carboxanilide, and a,a'-' Jan June -5 814 (1-937) P bisphenylazo-a,a-dimethy1diacetoacetic acid diethyl 15 ester. CHARLES B. PARKER, Primary Examiner. 

1. A PHENYLAZO COMPOUND SELECTED FROM THE GROUP CONSISTING OF A-PHENYLAZO-CYCLOPENTANONE-A-CARBOXYLIC ETHYL ESTER, A-PHENYLAZO-A-METHYLACETOACETANILIDE, APHENYLAZO-CYCLOPENTANONE-A-CARBOXANILIDE, AND A,A''BISPHENYLAZO-A,A''-DIMETHYL-DIACETOACETIC ACID DIETHYL ESTER. 